Metallurgy of metal sulfids.



E. A. ASHCROFT.

METALLURGY 0F METAL SULFIDS. APPLICATION FILED APR. 9, 1910.

1,01 1,900. Patented Dec.19,1911.

' perfectly recovered EDGAR ARTHUR ASHCROFT, 0F SOGN, NOB-WAY.

METALLUBGY OF METAL SULFIDS.

Specification of Letters fatent.

Patented Dec. 19, 1911.

Application filed April 9, 1910. Serial No. 554,511.

To all whom 'it may concern:

Be it known that I, EDGAR ARTHUR ASH- CROFT, subject of the King ofEngland, residing at Sogn, Norway, have invented certain new and usefulImprovements in the Metallurgy of Metal Sulfids, of which the followingis a specification.

This invention relates to improvements in the metallurgy of metalsulfids.

Sulfids of metals nearly free from gangue are produced in largequantities from the mechanical concentration of the well known BrokenHill refractory ores which are taken here as sufficiently illustrativeof similar ores which occur with slight modifications all over the worldand are the treatment herein described.

Two leading products from the concentrating mills are recognized in thearts today, viz: (A) zinc concentrates containing upward of 40% zinc andunder 12% lead .and some silver, and (B) lead concentrates of lead andun- Also in containing upward of 50% der 12% of zinc and some silver.smaller quantities. ucts such as slimes and middlings of varyingcomposition. In treating the proccss of zinc smelting in retort furnacesis the one generally employed and the leadv and silver and sulfur areeither lost or very imfrom the residue at great expense. (B) the processof lead smelting is nowalmost universally employed and the zinc andsulfur are lost. The intermediate products C) are at present onlycapable of economica treatment by mixing with other ores in smeltingfurnaces in trifling quantities or by being first converted bymechanical separation int? products resembling .either (A) or (B) incomposition.

The present invention has for its princi al object the more economicaltreatment 0 the zinc sulfid residues left after the treatment of theproducts A. and B. according to the method described in my U. S.applications Serial No. 554,508, filed April 9th, 1910, and Seriallie-551,509, filed April 9th, 1910. But either of the roducts A. B. orG. or any other metal sul (1 may also be treated without departing fromthis invention, it being self evident that if separate metals aredesired the sulfids must be separated. According to British Patent No.10829/ 1897 J. Swinburne has suggested the treatment of such products orthe original ore from whence they are derived by eleclikewise amenableto (C) intermediate proding ing the iron is however trolyze the meltreceiving the iron first into by obtained. metal being deposited from amixed chlorid trolyzing sulfids in a bath of fused chlorids andgettingofi sulfur and-metals. This reaction however requires a hightemperature (about 600700 C.) and very violent agitation of the melt toprevent settling and has never been carried out in practice.

I have discovered that a more practical and convenient process for theabove purpose is to so electrolyze the melt as to get off one or otherof the chlorids of sulfur and metals according to one of the followingreactions which will take place if the electrolysis is conducted at orabout the respectively stated temperatures.

1 MS+2MO1,=3M+SC1, Temp. 350C. 2 Ms+ Mo1,=2M+so1, 450 0. a 2MS+Mo1,:3M+s,o1, 550C.

The sulfur chlorid given ofi may be readily condensed, (assisted in thecase of the less stable products of reactions 1 and 2 by artificialcooling) and afterward reacted with metal sulfids as described inSwinburne and Ashcrofts U. S. Patent No. 691,822, dated January 28th,1902 producsulfur and metal chlorids the latter being added to theelectrolysis bath to compensate for the chlorids decomposed by the abovereactions. 'According to this invention, therefore, a process ofrecovering metals from a mixture containing other sulfids consists 1ntreating the mixture with a fused metallic chlorid and electrolyzing themelt at the low temperatures referred to so as to produce the metals andchlorids of sulfur.

The above process is very economical of electric energy and ofapparatus.

When zinc is the 'metal under recovery it is desirable to first removeany iron present from the fused chlorids to prevent contamination of thedeposlted metal and this may .be carried out by known methods ofpurification. The preferred method of eliminatto fractionally elecpuremolten zinc is afterward substituted from the iron lead alloy and purezinc there- When however lead is the and sulfid bath it is not necessaryto first remove the iron as the latter is always maintained in theferrous state by the reducingaction of the sulfids present and so doesnot interfere with the precipitation of lead as it The accompanyingdrawing is a diagram illustrating one method of carrying this inventioninto effect as applied for example to a zinc sulfid residue.

The ore from a bin A is fed both to an electrolytic vat B and to aconverter C. The ore enters the electrolytic vat at the inlet B throughwhich is also supplied the fused.

zinc chlorid. Chlorid of sulfur is evolved and passes out through theoutlet B and the metallic zinc is removed from the outlet B at thebottom of the electrolytic vat. The zinc sulfid residue passes from theore bin A through the inlet C to the converter, the chlorid of sulfurfrom the electrolytic vat is introduced through the twyer or other inletC to the converter. The sulfur chlorid reacts with the zinc sulfid inthe converter, the chlorin combining with the zinc to form zinc chloridand the sulfur being given oif. The reaction takes place according tothe following equation:-

ZnS+CCI =ZnCI +S and the resulting zinc chlorid is removed by the outletC from the converter and returned to the electrolytic vat.

The form of the apparatus can be varied to suit the conditions underwhich it is used. What I claim as my invention and desire to secure byLetters Patent is 1. A process of recovering metals from a mixturecontaining their sulfids which comprises treating the mixture with afused metallic chlorid and electrolyzing the melt at low temperature soas to and chlorids of sulfur.

2. A process of recovering metals from a mixture containing theirsulfids which comprises treating the mixture with a fused metallicchlorid and electrolyzing the melt at low temperature to produce themetals and chlorids of sulfur, condensing the chlorids of sulfur andreacting them with metal sulfids to produce sulfur and metal chlorids,findh adding the latter to the electrolytic 3. A process of recoveringzinc from a mixture containing zinc sulfid which comprises treating themixture With fused zinc chlorid and electrolyzing the melt at lowproduce the metals temperature to produce zinc and chlorid of sulfur.

4. A process of recovering zinc from a mixture containing zinc sulfidwhich comprises treating the mixture with fused zinc chlorid andelectrolyzing the melt-at low temperature to produce zinc and chlorid ofsulfur, and reacting the chlorid of sulfur with a mixture containing thezinc sulfid to form zinc chlorid and sulfur, the zinc chlorid beingadded to the electrolytic bath.

5. A process ofrecovering zinc from a mixture containing zinc sulfidwhich comprises treating the, mixture with fused zinc chlorid,electrolyzing the melt over a bath of molten lead so as to remove theiron as an alloy, subsequently electrolyzing the melt at low temperatureto produce zinc and chlorid of sulfur, and reacting the chlorid ofsulfur with a mixture containing the zinc sulfid to form zinc chloridand sulfur, the zinc chlorid being added to the electrolytic bath.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

EDGAR ARTHUR ASHCROFT.

